[開發] 螢幕座標轉地圖座標

[meya (落寞之心)]

一般的在Google Map上的應用，多半都是GeoPoint的座標轉成螢幕的Pixels座標，然後畫
圖在螢幕上，可是今天我想要反過來，就是我用手去碰觸螢幕上的地圖，然後抓出地圖上
被我碰到的點的座標是多少，範例如下：

(這個之前有po過，這次po的是改良版，加了myItemOverlay的置中圖示，方便辨認)

http://www.anddev.org/viewtopic.php?p=28140

OnTouchListener myOnTouchListener=new OnTouchListener(){
  public boolean onTouch(View mapView, MotionEvent m){
      int action=m.getAction();
      switch(action){
        case MotionEvent.ACTION_UP:
          int x=(int)m.getX();
          int y=(int)m.getY();
          double latspan=(mMapView01.getLatitudeSpan()/1.0E6);
          double lngspan=(mMapView01.getLongitudeSpan()/1.0E6);
          GeoPoint center=mMapView01.getMapCenter();
          double xpcent=(x/(double)mMapView01.getWidth());
          double ypcent=(y/(double)mMapView01.getHeight());
          double lat0=(center.getLatitudeE6()/1.0E6+(latspan/2.0));
          double lng0=(center.getLongitudeE6()/1.0E6-(lngspan/2.0));
          lat=lat0-(ypcent*latspan);
          lng=lng0+(xpcent*lngspan);
          //Log.i("x=",""+x);
          //Log.i("y=",""+y);
          GeoPoint newpoint=new GeoPoint((int)(lat*1E6),(int)(lng*1E6));
          // mMapView01.getController().zoomOut();

          /*Log.i("Map","Height"+mMapView01.getHeight());
          Log.i("Map","width"+mMapView01.getWidth());
          Log.i("Current","LatitudeSpane"+mMapView01.getLatitudeSpan());
          Log.i("Current","LongitudeSpan"+mMapView01.getLongitudeSpan());
          Log.i("center Longitude","is"+newpoint.getLongitudeE6());
          Log.i("center","Latitude is"+newpoint.getLatitudeE6());
          Log.i("new ","latitude "+lat);
          Log.i("new","longitude "+lng);
          Log.i("background","is"+mMapView01.getBackground());
          Log.i("Zoom in","works"); */

          //mMapView01.invalidate();
          mMapController01.animateTo(newpoint);
          //mMapController01.zoomIn();
          GeoPoint gp = null;
          gp = new GeoPoint((int)(lat*1E6),(int)(lng*1E6));


          //在地圖上加icon
          Drawable dr = getResources().getDrawable(R.drawable.star);
          dr.setBounds(-15, -15, 15, 15);
          MyItemOverlay mOverlay01= new MyItemOverlay(dr, gp);
          List<Overlay> overlays= mMapView01.getOverlays();
          overlays.clear();
          overlays.add(mOverlay01);

          break;
      }
      return false;
  }
};
mMapView01.setOnTouchListener(myOnTouchListener);




public class MyItemOverlay extends ItemizedOverlay<OverlayItem>{

        private List<OverlayItem> items = new ArrayList<OverlayItem>();

        public MyItemOverlay(Drawable arg0, GeoPoint gp) {
                super(arg0);
                // TODO Auto-generated constructor stub
                items.add(new OverlayItem(gp, "Title", "Snippet"));
                populate();
        }

        @Override
        protected OverlayItem createItem(int i) {
                // TODO Auto-generated method stub
                //return null;
                return items.get(i);
        }

        @Override
        public int size() {
                // TODO Auto-generated method stub
                //return 0;
                return items.size();
        }
}


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※ 編輯: meya            來自: 140.114.78.145       (07/26 22:33)